\documentclass{article}
\usepackage[x11names, rgb]{xcolor}
\usepackage[utf8]{inputenc}
\usepackage{tikz}
\usetikzlibrary{snakes,arrows,shapes}
\usepackage{amsmath}
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\usepackage[active,tightpage]{preview}
\PreviewEnvironment{tikzpicture}
\setlength\PreviewBorder{0pt}%
\usetikzlibrary{automata}%

\begin{document}
\pagestyle{empty}
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\enlargethispage{100cm}
% Start of code
\begin{tikzpicture}[>=latex',join=bevel,]
\tikzstyle{every state}=[draw=blue!50,very thick,fill=blue!20]%
\node (q0) at (337bp,634bp) [state] {$q_{0}$};
  \node (q8) at (135bp,106bp) [state] {$q_{8}$};
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  \node (q1) at (343bp,18bp) [state] {$q_{1}$};
  \draw [->] (q0) ..controls (289bp,608bp) and (239bp,580bp)  .. node[auto] {$buyer#submit$} (q2);
  \draw [->] (q0) ..controls (392bp,613bp) and (441bp,587bp)  .. (441bp,546bp) .. controls (441bp,546bp) and (441bp,546bp)  .. (441bp,106bp) .. controls (441bp,70bp) and (405bp,45bp)  .. node[auto] {$seller#submit$} (q1);
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  \draw [->] (q4) ..controls (124bp,340bp) and (124bp,324bp)  .. node[auto] {$auctionRegistrationService#answer$} (q5);
  \draw [->] (q3) ..controls (143bp,443bp) and (131bp,434bp)  .. (124bp,422bp) .. controls (120bp,415bp) and (119bp,406bp)  .. node[auto] {$\overline{auctionRegistrationService#process}$} (q4);
  \draw [->] (q2) ..controls (178bp,516bp) and (178bp,500bp)  .. node[auto] {$seller#submit$} (q3);
  \draw [->] (q1) ..controls (343bp,54bp) and (343bp,81bp)  .. (343bp,106bp) .. controls (343bp,370bp) and (343bp,370bp)  .. (343bp,370bp) .. controls (343bp,393bp) and (349bp,405bp)  .. (333bp,422bp) .. controls (316bp,439bp) and (255bp,448bp)  .. node[auto] {$buyer#submit$} (q3);
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\end{tikzpicture}
% End of code

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\end{document}
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